Sideloading an IPA bypasses the App Store's security vetting.
Assuming you have a legitimate IPA of Facebook version 244.0 or older, you would need: facebook ipa for ios 935 verified
For those interested in early access to new features, Facebook, like many developers, offers a beta testing program through TestFlight. This is a more secure way to get early versions of the app directly from the developer. Sideloading an IPA bypasses the App Store's security vetting